1. Field of the Invention
The present invention relates to a gaming machine, and in particular, to a gaming machine in which a game is conducted by rotating and driving reels on each of which various symbols are formed, like a slot machine.
2. Description of Related Art
Generally speaking, the slot machine mentioned above is constructed so that a plurality of reels are driven by operation of a start lever and stop buttons arranged according to each of the reels are pressed and operated, thereby the reels are stopped and the stopped symbols are aligned in an order of a predetermined winning combination, as a result, game media such as medals are obtained.
The above reels, for example, as disclosed in Japanese Unexamined Publication No. 10-71240, are rotatably supported in a reel unit and rotation drive and stop control of the reels are done by stepping motors arranged in the reel unit. Concretely, based on that the start lever is operated, rotational instruction signals are input to the stepping motors and the reels are started to rotate, thereafter when a player presses and operates the stop buttons, stop instruction signals are input to the stepping motors, thereby drive of the reels is stopped.
Concerning with the above drive/stop control of the reels, as well-known, in the slot machine, when the start lever is operated, internal lottery process is conducted in a CPU arranged on a control circuit board and a winning combination is actually determined. At that time, the CPU conducts stop control of the stepping motors so that the symbols are stopped with a stop symbol combination corresponding to the winning combination, or the CPU intentionally conducts stop control of the stepping motors so that the symbols are not aligned in an order of the stop symbol combination corresponding to the winning combination.
And since the above stepping motors drives and rotates the reels which the player sees and recognizes with high interest, performance and specification of the stepping motors have to be sufficiently considered. In general, as the stepping motors arranged in the reel unit of the slot machine, it is utilized a stepping motor of HB type (hybrid type) which has both merits of a stepping motor of PM type (permanent magnet type) having a relatively small size and capable of producing a relatively large torque and a stepping motor of VR type (variable reluctance type) without the permanent magnet, in which a rotation angle can be finely divided. For example, in a case that such stepping motor has a characteristic of 200 steps/one rotation, the stepping motor is driven by 1–2 phase excitation, thereby the stepping motor concludes to have a characteristic of 400 steps/one rotation and is utilized so as to produce such characteristic. According to such stepping motor, the rotation angle becomes 0.9 degrees per one step, thereby smooth rotation of the reel can be realized when the player sees and recognizes the symbols on the reel. In this case, when the reel is rotated at a constant speed (80 rpm), drive frequency thereof is set to 533.3 pps (400×80 rpm/60 sec).
By the way, as the stepping motor mentioned above, taking manufacturing cost of the reel unit into consideration, it is preferable to utilize the stepping motor with a construction as cheap as possible, for example, it is conceivable to utilize the stepping motor of PM type (permanent magnet type). However, this kind of cheap step motor has only rough resolution and less step number per one rotation. Therefore, if such stepping motor with intact performance is assembled in the reel unit, rotation smoothness of the reel lacks, thus there will occur a problem that a feeling of discomfort on visibility will be given to the player in comparison with a case of the above mentioned stepping motor. Especially, when the reel is started to rotate (accelerated) or stopped (decelerated), a rickety feeling is given to the player.